Repotting guide

When & how to repot Sempervivum montanum (Sempervivum montanum)

Also called Mountain houseleek.

More about sempervivum montanum

About Sempervivum montanum

Sempervivum montanum · also called Mountain houseleek · houseplant

Sempervivum montanum is a true alpine houseleek with small, soft-haired, resin-scented green rosettes that hug the ground. Native to high mountain screes, it is exceptionally cold-hardy and craves full sun and sharp drainage. It clusters into tight cushions via offsets, produces star-shaped reddish-purple flowers, and rots quickly in damp, shaded, or rich conditions.

Mature size: Rosettes 2-5 cm across (smaller than most houseleeks); cushions spread 20-25 cm wide. Flower stems 5-12 cm tall.

Watch for — Winter wet rot: Cold combined with damp soil rots the crown and roots. Keep almost completely dry through winter, use a free-draining gritty mix, and shelter from prolonged rain if grown outdoors.

How to tell sempervivum montanum needs repotting

Repotting on a calendar is less reliable than reading the plant. For sempervivum montanum, watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot sempervivum montanum

Every 2–3 years, into bone-dry mix. Sempervivum montanum's growth habit — evergreen, cushion-forming alpine succulent. small fuzzy rosettes multiply tightly by short offsets to build dense, low mats. each rosette is monocarpic, flowering once on a short stalk before dying and being replaced by its chicks. — sets the pace. Sempervivum montanum is a true alpine houseleek with small, soft-haired, resin-scented green rosettes that hug the ground. Native to high mountain screes, it is exceptionally cold-hardy and craves full sun and sharp drainage. It clusters into tight cushions via offsets, produces star-shaped reddish-purple flowers, and rots quickly in damp, shaded, or rich conditions.

What size pot to step sempervivum montanum up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Sempervivum montanum stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot sempervivum montanum

Spring or summer, while sempervivum montanum is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting sempervivum montanum

Repot dry. Do not water sempervivum montanum for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty very sharp, lean alpine/scree mix ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set sempervivum montanum at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep sempervivum montanum completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for sempervivum montanum

Sempervivum montanum wants very sharp, lean alpine/scree mix. Plant in a gritty, low-fertility blend — cactus compost mixed heavily with grit, pumice, or perlite. Montanum prefers a slightly acidic to neutral, lean substrate that drains instantly; avoid rich, peaty composts. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting sempervivum montanum — frequently asked questions

How often should you repot sempervivum montanum?

Every 2–3 years, into bone-dry mix for sempervivum montanum. Repot sempervivum montanum every 2–3 years into a snug pot of very sharp, lean alpine/scree mix, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does sempervivum montanum need?

When is the best time of year to repot sempervivum montanum?

Should you water sempervivum montanum after repotting?

No — not straight away. Repot sempervivum montanum into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise sempervivum montanum after repotting?

Not immediately. Wait about 3 weeks after repotting sempervivum montanum. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.